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general relativity

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Will Einstein's general theory of relativity hold true?

Scientists have for the first time measured the speed of gravity and tested Einstein's assumption - or have they?

This issue of Plus is a special, marking the occasion of Stephen Hawking's 60th birthday. Plus attended his Birthday Conference in Cambridge, where we interviewed some of the world's most influential mathematicians and physicists.

Plus is very proud to present Professor Stephen Hawking's own Birthday Symposium address.